11:30 AM - 11:45 AM
[SVC31-16] Observations of SP and tilt vatiations at Kibedani Geyser, Shimane Prefecture: Relationship between groundwater flow and eruption activity
Keywords:Geyser, Electric self-potential (SP), Tilt, Groundwater flow
"A temporal change in tilt, tremor" lasting several minutes is often reported just before phreatic eruptions. Additionally, Aizawa et al. (2022) reported that change in electric self-potential (SP) occurred near the eruption vent. SP change is interpreted as streaming potential generated by the movement of groundwater in subsurface porous media. Furthermore, Tanabe et al. (2023) reported that similar SP change occur just before intermittent hydrothermal water discharge (geyser activity) at the West Crater of Iwo-Yama volcano in 2021. Understanding groundwater flow in geysers is expected to provide insights into processes immediately preceding phreatic eruptions. However, since Tanabe et al. (2023) had only one observation point for SP and tilt measurements, it was unclear how these SP changes (groundwater flow) influence eruptions (the relationship between depth, direction, timing of groundwater flow, and eruption), and whether these SP changes a global phenomenon present at every geyser. To address this issue, we performed multi-parametric observations, including SP and tilt, at Kibedani Geyser as the first step towards predicting phreatic eruptions.
Kibedani Geyser erupt cold springs water (20 °C) due to the pressure of underground CO2 gas. We performed multi-parametric observations (optical camera, thermometer, SP, tilt, and acoustics) at Kibedani Geyser, Shimane Prefecture (Fig.1). Tiltmeters, SP sensors, and acoustic sensors were installed at three points.
Tilt and SP data recorded variations related to the geyser cycle (38 min). Analysis of tilt variation inferred a crack shaped pressure source SW-NE of the vent. From SP data, we interpreted groundwater moved toward the crack shaped pressure source before the overflow, and the amplitude decreased afterward.
Before the overflow, CO2 gas accumulated in the cavity, and the aperture allowed the inflow of groundwater. Finally, when gas pressure increased to the point that no more groundwater could inflow, overflow occurred. In this study, we demonstrated observations of SP and tilt, which are effective in understanding the relationship between intermittent discharge activity and groundwater flow.
[References]
・Aizawa K, Muramatsu D, Matsushima T, Koyama T, Uyeshima M, Nakao S (2022) Phreatic volcanic eruption preceded by observable shallow groundwater flow at Iwo-Yama, Kirishima Volcanic Complex, Japan. Commun Earth Environ 3:187. https://doi.org/10.1038/s43247-022-00515-5
・Tanabe H, Matsushima T, Aizawa K, Muramatsu D (2023) Multi-parametric observations of intermittent hydrothermal water discharge in West Crater of Iwo-Yama volcano, Kirishima Volcanic Complex, Japan. Earth Planets Space 75:75. https://doi.org/10.1186/s40623-023-01830-7
・Hurwitz S, Manga M (2017) The Fascinating and Complex Dynamics of Geyser Eruptions. Annu Rev Earth Planet Sci 45:31–59. https://doi.org/10.1146/annurev-earth-063016-015605
Kibedani Geyser erupt cold springs water (20 °C) due to the pressure of underground CO2 gas. We performed multi-parametric observations (optical camera, thermometer, SP, tilt, and acoustics) at Kibedani Geyser, Shimane Prefecture (Fig.1). Tiltmeters, SP sensors, and acoustic sensors were installed at three points.
Tilt and SP data recorded variations related to the geyser cycle (38 min). Analysis of tilt variation inferred a crack shaped pressure source SW-NE of the vent. From SP data, we interpreted groundwater moved toward the crack shaped pressure source before the overflow, and the amplitude decreased afterward.
Before the overflow, CO2 gas accumulated in the cavity, and the aperture allowed the inflow of groundwater. Finally, when gas pressure increased to the point that no more groundwater could inflow, overflow occurred. In this study, we demonstrated observations of SP and tilt, which are effective in understanding the relationship between intermittent discharge activity and groundwater flow.
[References]
・Aizawa K, Muramatsu D, Matsushima T, Koyama T, Uyeshima M, Nakao S (2022) Phreatic volcanic eruption preceded by observable shallow groundwater flow at Iwo-Yama, Kirishima Volcanic Complex, Japan. Commun Earth Environ 3:187. https://doi.org/10.1038/s43247-022-00515-5
・Tanabe H, Matsushima T, Aizawa K, Muramatsu D (2023) Multi-parametric observations of intermittent hydrothermal water discharge in West Crater of Iwo-Yama volcano, Kirishima Volcanic Complex, Japan. Earth Planets Space 75:75. https://doi.org/10.1186/s40623-023-01830-7
・Hurwitz S, Manga M (2017) The Fascinating and Complex Dynamics of Geyser Eruptions. Annu Rev Earth Planet Sci 45:31–59. https://doi.org/10.1146/annurev-earth-063016-015605